1. Field of the Invention:
The invention relates to a burner with feed ducts for homogeneous and heterogeneous reactants and burner cooling chamber placed peripherally in the area of the burner head, particularly for the production of synthesis gas.
2. Discussion of the Background:
A burner is shown in EP-OS 0 098 043. For better utilization of conventional petroleum in extracting low-boiling products or in exploitation of complementary raw materials such as very heavy oil or coal, conversion processes are being developed and used to an increasing extent.
One of the problems that occurs is the disposal of the resulting conversion residues, which, with decreasing feedstock quality and increasingly higher conversion rate, exhibit an increasingly higher percentage of harmful contents such as heavy metals and solids. The solid portions have gotten into the resulting residues by addition of catalysts, for example, in the processes of destructive or refining hydrogenation, whereby the solid portions are concentrated during the conversion process. In coal conversion, the solid portions are already partially present in the initial material in the form of socalled ash content. For example, in destructive hydrogenation of coal, the solid is also concentrated in the residue.
The residues of hydrogenation of carbonaceous material as well as the distillation of petroleums, bitumen and the like (but also of certain mineral oil fractions themselves) or even coal can be subjected to a conversion process by partial combustion and gasification.
To achieve an optimal conversion during gasification, the feedstock must arrive in the reaction zone as finely dispersed as possible. During oxidation of the gasification feedstock with a gas containing free oxygen and during heterogeneous conversions occurring simultaneously with steam added at the same time and optionally other components added, e.g., a moderator gas, the size of the contact surface between gas phase and fuel phase is decisive for the conversion that can be attained during the gasification reaction.
In the case of known gasification burners, the fine dispersion of the feedstock necessary for as high as possible a conversion of the gasification reaction is attained through a narrow constriction of the fuel intake with an appropriately high pressure drop and a high velocity in the atomizer nozzle. In the case of atomizing of abrasive media, such as residue suspensions containing solids from conversion processes, the high nozzle velocity necessary for an optimal atomizing would result in great wear and a correspondingly short service life of the burner.
Atomizing of solid suspensions over a narrow nozzle cross section, moreover, would result in a tendency toward clogging of the nozzle, an irregular delivery and a variable composition in the amount of product gas.
The gasification flame exhibits its highest temperature in the gasification reactor in the vicinity of the burner orifice. The exothermic, energy-releasing partial oxidation of the fuel can occur there only through the excess oxygen present directly on the burner orifice. As a result of the high flame temperature, strong thermal stress of the burner orifice results from radiation. In the interaction between the resulting elevated material temperature and the oxygen-containing atmosphere in the vicinity of the burner, there is a danger of high temperature corrosion occurring or at worst in case of insufficient heat removal of burning off the burner tip. The temperature stress can be reduced by raising the discharge velocity. However, with a high discharge velocity the danger is increased of back turbulence and, with it, ignition again in the vicinity of the burner.
When ash-containing fuel is used, the reactor temperature during gasification or during synthesis gas production is near or above the melting temperature of the resulting slag. For this reason, there is the danger of a slow slagging of the burner discharge opening, which can be accompanied by a change of the shape of the flame and a disturbance or impairment of the gasification process.